Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 2601.29.10Lecture 8 - MitochondriaMitochondria perform 2 functions within the cell1.They are the primary sites for ATP synthesis in the cell2.They have a key role in apoptosis - programmed cell deathMitochondria are actively transported along microtubules in some cellsMitochondria are anchored near sites of high ATP consumption in other cellsQuickTime™ and aYUV420 codec decompressorare needed to see this picture.Mitochondria are dynamic organellesRelative contributions of nuclear and mitochondrial genes to protein compositionMitochondria are organized into 4 distinct compartmentsQuickTime™ and aMPEG-4 Video decompressorare needed to see this picture.Mitochondria are organized into 4 distinct compartmentsCompartments of a mitochondrion compared with a bacteriumMitochondria are organized into 4 distinct compartments•Outer membrane:•Perforated with large channels (porins) that allow entry of molecules < 5000 kD•Enzymes involved in mitochondrial lipid synthesis•Intermembrane space:•Enzymes that use newly-made ATP to phosphorylate other nucleotides•Compartment into which H+ is pumpedMitochondria are organized into 4 distinct compartmentsMitochondria are organized into 4 distinct compartments•Inner membrane:•Folded into christae to maximize surface area•Proteins that carry out redox reactions of the electron transport chain•Proteins that synthesize ATP•Transport proteins that move molecules into and out of the matrix•Matrix:•Internal space containing enzymes for Krebs cycle•Contains mitochondrial DNA, special ribosomes, tRNAs, and enzymes required for gene expressionMitochondria are organized into 4 distinct compartmentsMitochondria catalyze a major conversion of energy by oxidative phosphorylationTextMitochondria use pyruvate or fatty acids to make energyPyruvate from sugars, fatty acids from fatsHigh energy electrons are generated via the citric acid (Krebs) cycleProtons are pumped across the inner mitochondrial membraneThe electron transport chain consists of 3 enzyme complexesThe electrochemical gradient of H+ across the inner membrane has 2 components:The proton gradient drives ATP synthesis TextATP sythase is a protein complex embedded in the inner mitochondrial membraneATP synthase acts as a rotary motorQuickTime™ and aSorenson Video decompressorare needed to see this picture.ATP synthase acts as a rotary motorQuickTime™ and aYUV420 codec decompressorare needed to see this picture.ATP synthase is a motor•Motor complex attached to glass and bound to fluorescent actin filament•ATP added and the complex is imaged by fluorescent microscopy•Actin filament is spun like a propellerThe proton gradient also drives coupled transportDefect in mitochondrial function is the cause for numerous inherited diseasesProblems Associated with Mitochondrial Cytopathies, 1 in 4000 children per yearBrainDevelopmental delays, mental retardation, dementia, seizures, neuro-psychiatric disturbances, atypical cerebral palsy, migraines, strokesNervesWeakness (which may be intermittent), neuropathic pain, absent reflexes, gastrointestinal problem (gastroesophogeal reflux, delayed gastric emptying, constipation, pseudo-obstruction), fainting, absent or excessive sweating resulting in temperature regulation problemsMusclesWeakness, hypotonia, cramping, muscle painKidneysProximal renal tubular wasting resulting in loss of protein, magnesium, phosphorous, calcium and other electrolytesHearCardiac conduction defects (heart blocks), cardiomyopathyLiver Hypoglycemia (low blood sugar), liver failureEyesVisual loss and blindnessEarsHearing loss and deafnessPancreasDiabetes and exocrine pancreatic failure (inability to make digestive enzymes)SystemicFailure to gain weight, short stature, fatigue, respiratory problems including intermittent air
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